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triggering keyframes with an expression
Hello.
I am trying to trigger an expression (or simply keyframes) using a slider.
I am making a graphic sliding scale consisting of a line of squares. I want to be able to increase a slider, and have each square animate when it’s respective number is passed on the slider.
So far, I’ve got them wobbling using an expression I got from Dan Ebberts at Motion Script.
But now I want to fade out a color overlay layer style’s opacity when the square is triggered.
Basically I need an expression that says:when SliderValue > X turn ColorOverlay to 100% and then fade out slowly over time.
If SliderValue < X turn ColorOverlay to 0Any thoughts? Thank you
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3 Replies
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You were a little sparse on the details, but it’s going to look something like this:
sliderVal = thisComp.layer("controls").effect("Slider Control")("Slider");
triggerVal = 50;
fadeTime = 1.5;
above = false;
frame = timeToFrames();
while (true){
t = frame * thisComp.frameDuration;
if (above){
if (triggerVal > sliderVal.valueAtTime(t)){
frame++;
break;
}
}else if (triggerVal <= sliderVal.valueAtTime(t)){
above = true;
}
if (frame == 0){
break;
}
frame--;
}
if (! above)
value
else
linear(time - t,0,fadeTime,100,0);
Dan
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Thanks Dan, that was exactly what I was looking for. I really appreciate the help.
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Hi Dan,
That is actually exactly what I was asking for, but I’m now realizing that it is not right for what I’m doing. I tried to figure out how to change the expression to match my needs but I’m running up against a wall.
Basically I’m creating a slider that consists of a row of small whites cubes. As I increase my slider control the cubes individually wobble, and turn orange. The decay of the wobble is perfect, but I’m now realizing that as long as the slider value is up the cubes need to stay full orange, once the slider falls below their number, they need to fade back out to white.
So I think the expression needs to tell the opacity to change to 100% once the sliderVal >= triggerVal, and remain at that value until the sliderVal falls below the trigger val, at which point the opacity should begin to fade to zero.
I hope this is enough information. And again, thank you so much for your expertise — your website is the reason I am brave enough to even try using expressions.
Ken
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